Electric circuit breaker



2 sheets-sheet 1 Fig. 5.

S. R. SMITH, JR

ELECTRIC CIRCUIT BREAKER June 7, 1949.

Filed lay 23. Fi

Sdrwey F?. Smith by fw/ 511W H15 Attorney.

June 7, 1949. s. R. SMITH, JR

ELEcTRIc CIRCUIT samen K 2 Sheets-Sheet 2 Filed lay 25. 1944 r'wventor`.Sidney R. Smith Jr?, by )VMC His Attorney.

yPatented June 7, 19149 UNITED STATES PATENT OFFICE ELECTRIC CIRCUITBREAKER Sidney n. smith, Jr., Pittsfield, Mass., minor to GeneralElectric Company, a corporation of New York Application May 23, 1944,Serial No. 536,872

I extent in the protection of high tension electric Devices of this kindin general comcircuits. prise replaceable fusible means mounted within asuitable holder and they are usually located in close proximity to thehigh tension conductors as a consequence of which they are relativelyinaccessible for inspection and maintenance. Dimculties have beenencountered in providing fuse cutouts having an electric fuse convenientfor installation and inspection and at the same time capable of beingremovable and replaceable. In any event, an abnormal electricalcondition occurring on a circuit protected by a fusecutout will destroythe fuse and hence require replacement thereof. Although recentexperimentation and research have reduced thel cost of the replaceableelements, nevertheless such cost is still appreciable and it would bedesirable to provide a fuseless cutout which would automaticallyinterrupt the circuit under abnormal electrical conditions and yetwherein it is unnecessary to replace any elements after the protectiveoperation of such cutouts, as is necessary with the fuse cutouts of theprior art.

It is an object of my invention, therefore, to provide a new andimproved circuit breaker adapted to replace the fuse cutouts of theprior art,

It is another object of my invention to provide a new and improvedfuseless cutout which is simple and compact, economical in construction,which gives an immediate and reliable indication of the actuation andcondition thereof, and which may be used in connection with prior arthousings for fuse cutouts.

It is another object of my invention to provide a fuseless cutout of thevacuum type which may be used in place of the fuse cutouts of the priorart.

Further objects and advantages of my inven- 3 Claims. (Cl. 20o-113) tionwill become apparent as the following description proceeds and thefeatures of novelty which characterizes my invention will be pointed outwith particularity in the claims annexed to and forming a part of thisspecification.

For a better understanding of my invention, reference may be had to theaccompanying drawings in which Fig. 1 is a view of the upper portion ofan electrical device with which my invention is associated; Fig. 2 is anenlarged sectional view of a fuseless cutout of my invention in theclosed -circuit position; Fig. 3 is a view looking at the inside of thedoor or cover of the housing of the fuseless cutout of my invention;Fig. 4 is a partial view similar to Fig. 2 illustrating the fuselesscutout in the open circuit position; Fig. 5 is a sectional view similarto Fig. 1 with the housing removed, of a modification of my invention,and Figs. 6 and 7 are partial views of the modication illustrated inFig. 5 showing different operating conditions thereof.

Although my invention is adapted for use wherever fuse cutouts of theprior art have been used, either supported'from a pole, cross-arm, orthe like, I have chosen to illustrate my invention as supported on theinsulating bushing of an electrical apparatus such as a transformer orthe like.

Referring now to Fig. 1, the transformer I0 is illustrated as beingprovided With a cover I I upon which is mounted a high voltage bushingI2 having a terminal with a suitable extension I3 Lsee Figs. 2 and 4) atthe upper end thereof. Mechanically supported from the terminalextension I3 is an electric circuit interrupting device I4 embodying myinvention.

Electric circuit interrupting device I4 preferably comprises a housingI5 which may be substantially identical with the housing disclosed inHermann Patent 2,163,398, granted June 20, 1939, and assigned to thesame assignee as the present application. Housing I5 is preferablyformed of porcelain or other suitable insulating material and isprovided with an integrally formed electric creepage and gas barrier I6disposed between stationary contact assemblies I1 and IB supported inspaced relationship in housing I5.

The contact assembly I1 includes a line terminal I9 adapted to have aline conductor or lead fastened thereto by means of a suitable clampingscrew 20. This line conductor or lead.

not shown, may enter the housinglor casing I5 through an opening 2I (seeFlg.'1) which opening is in alignment with terminal I9. Contact assemblyI1 further includes a contact nger 22 backed up by Vmeans oi' a' springstrip 23 which serves to press the contact nnger 22 downwardly. Inaddition, contact assembly I1 `includes a terminal clip '24 which isarranged to receive the ilanged terminal cap 25 of my improved circuitinterrupter which is similar to the terminal caps of the fuse holders ofthe prior art. The terminal clip 24, the spring strip 23, the contactlinger 22 and the line terminal I9 are unitedto form the unitary contactassembly I1 which is suitably cemented into a recess 29 in the upperrear wall withinhousing I5.

The lower terminal assembly I3 really comprises a hinge bracket 21 whichserves as the lower terminal contact of the circuit interrupter andforms an integral part of the electrically conductive bolt 29 whichextends outwardly through an opening 29 in the rear wall of casing orhous- V ing I5 and which is xedly anchored in the opening 29 by means ofsuitable cement indicated at 39. The outer end ofthis bolt 28 isthreaded for the reception of a clamping nut 3I and a lock washer 32 sothat cutout housing I5 may be mechanically supported from terminalextension I3 of transformer I9. With this arrangement the hinge bracket28 which serves as a lower contactof thel circuit interrupter of myinvention, is electrically connected to the transformer terminalextension I3. Preferably the live exposed portions of terminal extensionI3 and conductive bolt 28 are covered by a suitable insulating shield 33which may be similar to that disclosed and claimed in Patent No.l2,409,042, issued October 8, 1946, to Benjamin R. Hermann, and assignedto the same assignee as the present application.

It should be understood that as far as my invention is concerned,housing I5 might also be constructed in accordance with the housingdisclosed in United States Letters Patent 2,081,813, granted May 45,1937, upon an application of Benjamin R. Hermann and assigned to thesame assignee as the present application.

The open side at the front of housing I5 is closed by means of a door,or cover 34 preferably constructed of insulating material and havinggenerally the same shape and design as the doors or covers of enclosedfuse cutouts of the prior art, whereby this door and the apparatusassociated therewith may replace the doors or covers of the prior artconstructions or at least be interchangeable therewith. This door 34supports on one face an electric circuit interrupter generally indicatedat 35 and described in greater detail hereinafter. On the other face ofthe door or cover 34 there is formed an eyelet handle 36 which mayeither be grasped manually or engaged by a suitable switch stick (notshown). The circuit breaker or interrupter 35 when in the closedposition completes the electrical circuit between contact or terminalassemblies Il and I8, respectively.

Suitably bolted to the lower inside face ofdoor 34 is a U-shaped member31 having a hookshaped extension 38 for engaging the hinge pin 39supported by hinge bracket 21. With this arrangement door or cover 34'which, as will be described, supports circuit interrupter 35, is adaptedto be pivotally supported by hinge bracket 21 in such a manner that thedoor or cover 34 may be pivotally moved to either its open or closedposition and furthermore bodily lremoved from casing or housing I5whereupon 'I preferably closed by a flexible diaphragm 4I fastened tohousing 49 by means of a suitable seal. The upper end of housing 49 isclosed by a metal cover 42 also suitably connected so that glass casingor housing 49 may be evacuated to a high degree of vacuum. Flxedlymounted within the upper end of evacuated housing 49 is ya cup-shapedstationary contact 43. This contact has a hollow rod-like extension 44which extends out of evacuated housing 4'9. A passageway 45 withinextension 44 connects the interior of housing 49 with the exterior sothat the housingmay be evacuated to a high degree after which the end ofextension 44 is sealed off exteriorly of housing or casing 49 as isindicated at 46.

In order to supportthe circuit interrupter 35 fromdoor or cover 34rod-like extension 44ertends through an opening 41 in a projection 4'8mounted on the inside face of cover 34. Any suitable means for rigidlyfastening rod-like extension 44 to projection 49 may be provided. Asillustrated in Fig. 2, rod-.like extension 44 is threaded so thatflanged cap 25, which is internally threaded, and nut 44 may be suitablyfastened thereto. Flanged cap 25 is removed so that the rod-likeextension 44 may be inserted through opening 41 in projection 4'9, andproiection 48 can-then be clamped between nut 44' and flanged cap 25.Cap 25 connected to rodlike extension 44 forms the upper contact of thecircuit breaker which is adapted to be electrically engaged by contactringer 22 when the cover 34 is in the closed position shown.

Cooperating with stationary cup-shaped contact 43 is movable contact 49supported on a rod 59 which extends through exible diaphragm 4I but insealed relationship therewith. It will be understood by those skilled inthe art that only a very small movement which may be of the order of al,inch separation between contacts 43 and 4'9 is required to interrupthigh currents in a high vacuum. This relatively small movement ispermitted by flexible diaphragm 4 I. A suitable disk 5I is mounted onrod 59 within vacuum housing 49 to prevent the arc products fromimpinging against the flexible diaphragm. The reciprocal movement of rod59 and contact 49 is guided by a member 52 supported by U-shaped member31 or, if desired, formed integrally therewith. Member 52 is preferablyformed of insulating material or at least the opening therein throughwhich rod 59 reciprocates, is hushed with insulating material.

With the arrangement described thus far, it is obvious that atmosphericpressure will bias contacts 49 and 43 into engagement. I provide aspring 53 which is compressed between member 52 and a washer 54 held onrod 59 by pin 55 which provides a suiiicient force to overcomeatmospheric pressure and bias contacts 43 and 49 to the open positionshown in Fig. 4.

In order to hold or latch the contacts 43 and 49 in the closed positionshown in Fig. 2, I provide a latching means which comprises a currentresponsive means comprising U-shaped bimetallic element 56 best shown inFig. 3, a member A5l preferably formed of molded insulation and slidableon rod `50, and a suitable spring means 58.

lSpring means 58 is 4slidable on rod 50 with one end engageable withiiexible diaphragm 4'l, while the other end is engageable with the upperportion of latching member 51. The U-shaped bimetallic element 55 issuitably fastened, as indicated at 59, to door or cover 34. vA sort ofroller element 55' onl bimetallic element 58 is adapted to engage aVprojection Il on slidable member 51 when it is moved to its uppermostposition indicatedV in Fig. 2. In this position spring 58 is compressedso that diaphragm. is moved upwardly to hold contacts 43 and 49 in theclosed position. One leg of the U-shaped bimetallic element 55 iselectrically connected to rod 50 by means of a conducto;` while theother leg of the U-shaped bimetallic element 58 is electricallyconnected by conductor 62 to U-shaped member 31. U-shaped bimetallicelement 55 is very similar to the arrangement disclosed and claimed inU. S. Letters Patent,2,273,764, Salter, assigned to the same assignee asthe present application.

With the above arrangement of U-shaped bimetallic element 55 the currentflowing throughv circuit interrupter 35 must ilow through bimetallicelement 55. Excess currents will cause it to deflect to the positionshown in Fig. 4 whereupon roller 56 becomes disengaged from projection88 and spring 53 then causes relative separation of contacts. and 49 tothe position indicated in Fig. 4 with the consequent interruption of thecurrent flowing between terminalv assemblies l1 and i8.

In order to indicate the operating condition of circuit interrupter 35,slidable member 51 is provided with an extension 83 which may besuitably colored in a conspicuous manner. When the circuit interrupteris-in the closed position shown in Figs. 2 and 3 the indicator 83 ismoved completely within housing l5 and is not visible. However, uponoperation of the current responsive latching means including bimetallicelement 56, slidable member 51, and indicator 63 move downwardly to theposition shown in Fig. 4, with the indicator. 83 clearly visible. Itwill be observed that the movement of slidable element 51 is many timesgreater than thatA of rod 58 and this movement is limited by theengagement of slidable member 51 with member 52, as shown in Fig. 4. Theindicator 63 also provides a handle for resetting the circuitinterrupter 35. As soon as bimetallic element 56 has cooled sufficientlyfollowing a circuit interruption the circuit interrupter may be reclosedby merely pushing upwardly on indicator 53 until roller 58 again engagesprojection i0. Preferably such reclosing operation is performed Whilethe door 34 and associated circuit interrupter 35 are removed fromhousing l5. When the contacts 43 and 48 are reclosed the door or covermay be replaced and moved to the closed position in the same manner asthe doors or covers of the enclosed fuse'cutouts of the prior art. Withmy arrangement, however, no replacement of a burned out fusible elementis required.

The operation of the fuseless cutout of my invention will be obviousfrom the detailed description included above and, as will be obviousfrom this description, the present invention provides pronouncedadvantages over fuse cutouts of the prior art in that it is unnecessaryto replace any parts before the circuit may again be complated aftercircuit interruption, it being merely necessary for the lineman toreclose the circuit interrupter in the manner described above. Also anindication of the condition ofV thefuseless cutout is at all timesevident to the lineman.

Some times it is desirable in enclosed cutout devices to open the dooror cover following a ciri copending application, Serial No. 459,791, led

September 26,' 1942, now Patent 2,357,853, and assigned to the same"assignee as the present application, I f

Although I have disclosed the current or thermal-responsive means of myinvention as a bimetallic element 56, it will be obvious that othercurrent .or thermal -responsivemeans might equally well be employed,such forexample as are disclosed in the copendin'g application of GeorgeF. Lincka'Serial No. 522,584, filed February 16, 1944, and assigned tothe samefassignee as the present application or in Figs. 5, 6 and '1 ofthe drawings of the present application'. Also in accordance with theabove mentioned Lincks application, my fuseless cutout maybe of theautomatic reclosing type if desired.

InvFigs. 5, 6 and '1 of the drawings, I havedisclosed a modliication ofthe vacuum type i useless cutoutof my invention. Since the housing forthe fuseless cutout shown in Figs. 5, 6 and '1 would be substantiallyidentical with the housing'of Fig. 2, it has been omitted for the sakeof simplicity in the drawings. As in the fuseless cutout of Fig. 2, a.door or cover 66 is provided, having a manually engageable handle G1. AU-shaped hinge support 68 is fastened to the lower inside face of door56 by means of screws'89. This U- shaped hinge support is provided witha hookshaped portion 10 similar to the hook-shaped portion 38 of Fig. lwhich is engageable with ,the hinge pin 39. A suitable support H isbolted to the inside face of door 56 near the upper end thereof forsupporting in any suitable manner the stationary contact 12 ofthecircuit interrupter 13 mounted on door 66. `A vterminal cap 14electrically connected to stationary contact 12 is provided so as to beengageable by the contact nger'22 and spring clip 24l of upper `contactassembly l1.

Stationary contact 12 extends into an evacuated envelope -15 preferablyconstructed4 of suitable insulating material, such as glass or the like.A suitable seal between stationary contact 12 and evacuated envelope 15ls provided. Movably mounted in evacuated envelope 15 is movable contact18 which is attached to a tubular switch arm 11. This switch arm 11extends through and preferably is brazed or otherwise suitably sealed toa diaphragm 18 which is suitably sealed to the lower end of evacuatedenvelope 15. When the vacuum switch comprising envelope 15 and contacts12 and 16 is assembled, it is evacuated to a high degree of vacuumthrough tubular switch arm 11 after which the tubular switch arm isflattened and sealed exteriorly of the casing or envelope 15 asindicated at 19. The lower end of evacuated envelope 15 is additionallysupported from door 85 by means of a spring clip 80 suitably fastened todoor 55 as indicated at 8| in Fig. 5.

In order to bias relatively separable contacts ofinsulating material 82which is disposed so that the end of switch armv 11 extends'into theupper end of the bore in tube 82. A suitable washer 83 on the upper endof tube l2 engages with the emerged flattened portion 15 of switch

